Chuck

ABSTRACT

A chuck includes a generally cylindrical body having a nose section and a tail section. A plurality of jaws are movably disposed with respect to the body to and away from the chuck&#39;s axial bore. A generally cylindrical sleeve is in driving communication with the jaws. The sleeve engages the body or the jaws by a first set of interengaged threads so that relative rotation between the first threads drives the jaws toward or away from the chuck axis. The sleeve engages the body or the jaws by a second set of interengaged threads so that relative rotation between the second threads drives the jaws toward or away from the chuck axis. The first thread set defines a first pitch so that when the jaws close, the first threads rotationally lock in the closing direction. The second thread set defines a second pitch that is higher than the first pitch so that when the jaws close, the second threads are relatively rotatable in the closing direction.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.10/172,694, filed on Jun. 14, 2002 now U.S. Pat. No. 6,540,236, which isa continuation of patent application Ser. No. 09/523,426 filed Mar. 10,2000 now Pat. No. 6,428,018, the entire disclosures of which areincorporated by reference herein.

BACKGROUND OF THE INVENTION

The present invention relates generally to chucks for use with drills orwith electric or pneumatic power drivers. More particularly, the presentinvention relates to a chuck of the keyless type which may be tightenedor loosened by hand or by actuation of the driver motor.

Both hand and electric or pneumatic tool drivers are well-known.Although twist drills are the most common tools used with such drivers,the tools may also comprise screwdrivers, nut drivers, burrs, mountedgrinding stones, and other cutting or abrading tools. Since the toolsmay have shanks of varying diameter or may have a polygonalcross-section, the device is usually provided with a chuck that isadjustable over a relatively wide range. The chuck may be attached tothe driver by a threaded or tapered bore.

A wide variety of chucks have been developed in the art. In one form ofchuck, three jaws spaced circumferentially approximately 120° apart fromeach other are constrained by angularly disposed passageways in a bodyattached to the driveshaft. The chuck is configured so that rotation ofthe body in one direction with respect to a constrained nut forces thejaws into or away from gripping relationship with a tool shank. Such achuck may be keyless if it can be tightened or loosened by manualrotation. Examples of such chucks are disclosed in U.S. Pat. Nos.5,125,673 and 5,193,824, commonly assigned to the present assignee andthe entire disclosures of which are incorporated by reference herein.Various configurations of keyless chucks are known in the art and aredesirable for a variety of applications.

FIG. 2 illustrates, in cross-section, a typical chuck jaw constructionin which each of three jaws 200 includes a back surface 202 and anopposing tool-engaging surface formed by a ridge 204 disposed generallyparallel to the chuck axis. Two generally planar side surfaces 206extend from ridge 204 to the back surface. The side surfaces on each jaw200 define a 120° angle δ extending through the jaw. Thus, each sidesurface on a jaw 200 is parallel to a side surface of an adjacent jaw.When the chuck is moved to its fully closed position as shown in FIG. 2,the jaw side surfaces abut each other.

Other tool-engaging surfaces are known. For example, the tool-engagingsurface may be formed by an inner ridge parallel to the chuck axis andtwo outer ridges parallel to the inner ridge. A pair of respectivetroughs sit between the inner ridge and the outer ridges so that thejaw's cross-section is in the shape of a W. Generally, side surfacesthat extend from the outer ridges to the jaw's back surface define a120° angle between them through the jaw so that each side surface isparallel to the side surface of its adjacent jaw.

SUMMARY OF THE INVENTION

The present invention recognizes and addresses disadvantages of priorart construction and methods.

Accordingly, it is an object of the present invention to provide animproved chuck for use with a powered driver.

This and other objects are achieved by a chuck for use with a manual orpowered driver having a rotatable drive shaft. The chuck includes agenerally cylindrical body having a nose section and a tail section. Thetail section is configured to rotate with the drive shaft. The nosesection has an axial bore formed therein. A plurality of jaws aremoveably disposed with respect to the body to and away from the axialbore. A generally cylindrical sleeve is in driving communication withthe jaws so that rotation of the sleeve with respect to the body in aclosing direction moves the jaws toward the chuck axis and so thatrotation of the sleeve with respect to the body in an opening directionmoves the jaws away from the chuck axis. The chuck includes a first setof interengaged threads by which the sleeve engages one of the body andthe jaws so that relative rotation between the first threads drives thejaws toward or away from the chuck axis. The chuck includes a second setof interengaged threads by which the sleeve engages one of the body andthe jaws so that relative rotation between the second threads drives thejaws toward or away from the chuck axis. The first thread set defines afirst pitch so that when the jaws close, the first threads rotationallylock in the closing direction. The second thread set defines a secondpitch that is higher than the first pitch so that when the jaws close,the second threads are relatively rotatable in the closing direction.

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate one or more embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appendeddrawings, in which:

FIG. 1 is a plan view partly in section, of a chuck constructed inaccordance with an embodiment of the present invention;

FIG. 2 is a cross-sectional view of prior art chuck jaws;

FIG. 3 is a cross-sectional view of jaws for use in a chuck constructedin accordance with an embodiment of the present invention;

FIG. 4 is a cross-sectional view of jaws for use in a chuck constructedin accordance with an embodiment of the present invention;

FIG. 5 is a plan view, partly in section, of a chuck constructed inaccordance with an embodiment of the present invention;

FIG. 6 is an exploded view of the chuck as shown in FIG. 5;

FIG. 7 is a plan view, partly in section, of a chuck in accordance withan embodiment of the present invention;

FIG. 8 is a plan view, partly in section, of the chuck as in FIG. 7;

FIG. 9 is a plan view, partly in section, of the chuck as in FIG. 7;

FIG. 10 is an exploded view of the chuck as in FIG. 7;

FIG. 11 is a plan view of a thrust plate for use in the chuck as in FIG.7;

FIG. 12 is a plan view, partly in section, of a chuck in accordance withan embodiment of the present invention; and

FIG. 13 is an exploded view of the chuck as in FIG. 12.

Repeat use of reference characters in the present specification anddrawings is intended to represent same or analogous features or elementsof the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference will now be made in detail to presently preferred embodimentsof the invention, one or more examples of which are illustrated in theaccompanying drawing. Each example is provided by way of explanation ofthe invention, not limitation of the invention. In fact, it will beapparent to those skilled in the art that modifications and variationscan be made in the present invention without departing from the scope orspirit thereof. For instance, features illustrated or described as partof one embodiment may be used on another embodiment to yield a stillfurther embodiment. Thus, it is intended that the present inventioncovers such modifications and variations as come within the scope of theappended claims and their equivalents.

Referring to FIG. 1, a chuck 10 includes a front sleeve 12, an optionalrear sleeve 14, a body 16 and jaws 18. Body 16 is generally cylindricalin shape and includes a nose or forward section 20 and a tail orrearward section 22. An axial bore 24 is formed in nose section 20 andis somewhat larger than the largest tool shank that the chuck isdesigned to accommodate. A threaded bore 26 is formed in tail section 22and is of a standard size to mate with the drive shaft of a powered orhand driver (not shown). The bores 24 and 26 may communicate at acentral region of body 16. While a threaded bore 26 is described, suchbore may be replaced with a tapered bore of a standard size to mate witha tapered drive shaft. Furthermore, the body may be formed integrallywith the drive shaft.

A plurality of passageways 30 are formed in body 16 to accommodate eachjaw 18. Preferably, three jaws 18 are employed, and each jaw isseparated from the adjacent jaw by an arc of approximately 120°. Theaxes of passageways 30 and jaws 18 are angled with respect to the chuckaxis 31 but intersect the axis at a common point ahead of chuck body 16.Each jaw 18 has a tool engaging surface that is generally parallel tothe axis of axial bore 24, which is axis 31 of chuck body 16. Each jaw18 also defines threads 34 on its opposite or back surface.

Body 16 includes a thrust ring 36 which may be integral with the body.Thrust ring 36 includes a forward face that may include a seatingsurface for engagement with the inner race of a self-containedantifriction bearing assembly 42. Bearing assembly 42 may comprise anysuitable construction, for example a bearing assembly of the typedescribed in U.S. Pat. No. 5,348,318, incorporated by reference herein.Thrust ring 36 includes a plurality of jaw guideways 50 formed aroundits circumference to permit retraction of jaws 18.

A nut 60 includes threads 62 for mating with threads 34 on jaws 18whereby when the nut is rotated with respect to the body, the jaws areadvanced or retracted in the jaw passageways. Front sleeve 12 includes ametal annular collar 63 that is co-molded with the sleeve and that ispressed onto the nut so that the nut rotates with the sleeve. It shouldbe understood that various sleeve and nut configurations may beemployed. For example, sleeve 12 may be pressed onto nut 60 withoutcollar 63. Furthermore, while a one-piece nut is illustrated, atwo-piece nut configuration may be used in conjunction with a collar 63where the chuck body receives a two-piece nut within an annular groove.Still further, sleeve 12 may be loosely fitted over body nose section 20and may include drive ribs that engage drive slots in the nut so thatthe front sleeve rotationally drives the nut.

Returning to FIG. 1, a nosepiece 58 is pressed onto nose section 20 ofbody 16 to maintain nut 60 axially in position. Since sleeve 12 ispressed onto nut 60, nosepiece 58 also retains sleeve 12 in position.Nosepiece 58 defines a rear frustoconical surface 59 to allow passage ofjaws 18 rearward of body passageways 30. While nosepiece 58 is pressedonto body 16 as shown in FIG. 1, it should be appreciated that thenosepiece could also be secured by snap fit, threading or the like.Nosepiece 58 is exposed when the chuck is assembled and is preferablycoated with a non-ferrous metallic coating to prevent rust and toenhance its appearance.

Tail section 22 of body 20 can include a rear cylindrical portion havinga knurled surface 64 thereon for receipt of rear sleeve 14. The rearsleeve may be pressed onto the knurled surface or could be retained inplace by press fit without knurling or by use of a key. It could also beretained by crimping, staking, riveting, threading or any other suitablesecuring mechanism. Where front and rear sleeves 12 and 14 are replacedby a single sleeve extending substantially the length of body 16, aretaining disk may be pressed or otherwise retained on the tail sectionto maintain the sleeve on the body in the rearward direction.

The outer circumferential surface of sleeve 12 may be knurled or may beprovided with longitudinal ribs or other protrusions to enable theoperator to grip it securely. In like manner, the circumferentialsurface of rear sleeve 14, if employed, may be knurled or ribbed ifdesired. The front and rear sleeves may be fabricated from a structuralplastic such a polycarbonate, a filled polypropylene, for exampleglass-filled polypropylene, or a blend of structural plastic materials.Other composite materials such as, for example, graphite filledpolymerics could also be suitable in certain environments. Further, thesleeves may be constructed from suitable metals, such as steel. As wouldbe appreciated by one skilled in the art, the materials from which thechuck of the present invention is fabricated may depend upon the end useof the chuck, and the above are provided by way of example only.

FIG. 3 provides a cross-sectional illustration of jaws 18 along thelines 3—3 as shown in FIG. 1. Each jaw includes a back surface 66 and atool-engaging surface defined by a ridge 68 parallel to chuck axis 31.Each jaw includes two side surfaces 70 that extend from the jaw'stool-engaging ridge 68 to its back surface 66. Each jaw's side surfaces70 are disposed symmetrically on either side of a plane 72 that includeschuck axis 31 and the jaw's tool-engaging ridge 68. That is, plane 72evenly splits the angle between a jaw's side surfaces. Each side surfaceis generally planer. That is, a side surface may incidentally deviatefrom an ideal plane such that the side surface would not typically biteinto a tool shank.

Where chuck 10 includes three jaws, side surfaces 70 of each jaw 18define an angle δ through the chuck that is greater than 120°. Where thechuck includes a different number of jaws, the angle is greater than360° divided by that number. Accordingly, side surfaces 70 are notparallel to side surfaces of their adjacent jaws and do not fully abutthose side surfaces when the chuck is in a fully closed position asshown in FIG. 3.

Because opposing side surfaces 70 of adjacent jaws 18 diverge from eachother from jaw back surfaces 66 to the tool-engaging surfaces, a toolshank that is placed into the chuck bore, but that is offset from chuckaxis 31 so that it sits between opposing side surfaces, tends to bepushed back toward the chuck center axis as the jaws close. This isparticularly advantageous in a fast-closing chuck as described below.

The magnitude of angle δ may depend on the chuck's construction. Forexample, chucks having a nose section axial bore within a range ofapproximately 10 millimeters in diameter to 13 millimeters in diametermay have jaws with side surfaces that define an angle δ within a rangeof 130° to 140°. In two exemplary embodiments, jaws of a chuck having a10 mm capacity define side surface angles δ of approximately 130°, andjaws of a chuck having a 13 mm capacity define angles δ of approximately136°. When the jaws of the 10 mm chuck fully close on each other, theirridges 68 define a circle of approximately 1 mm diameter. Thus, the jawsare able to securely hold tool shanks larger than 1 mm. Thecorresponding diameter for the 13 mm chuck is approximately 1.5 mm.Angle δ may vary from 130° and 140° for these type chucks, depending onthe minimum diameter tool shank the chuck must grip. Angle δ may alsovary with the chuck axial bore diameter, for example ranging from 125°to 145° for exemplary chucks slightly smaller than 10 mm in capacity andslightly larger than 13 mm in capacity, respectively.

It should be understood that various tool-engaging surfaces may be usedon the jaws. For example, referring to FIG. 4, the tool-engaging surfaceof each jaw 18 includes an inner ridge 74 and two outer ridges 76disposed parallel to chuck axis 31. Each outer ridge 76 is separated bya trough from inner ridge 74 so that the tool-engaging surface defines aW-shaped cross-section. As shown in FIG. 4, angle δ between each pair ofside surfaces 70 is greater than 120°. In still further embodiments, theplanar side surfaces do not necessarily extend entirely back to the jawback surface.

It should also be understood that jaws as described herein may be usedwith a variety of chuck configurations. For example, referring to FIGS.5 and 6, a chuck 110 having jaws 18 as described above with respect toFIGS. 3 and 4 includes a front sleeve 114, an optional rear sleeve 116and a plurality of jaws 18. A body 120 is generally cylindrical in shapeand includes a nose or forward section 122 and a tail or rearwardsection 124. An axial bore 126 is formed in the nose section and issomewhat larger than the largest tool shank that the chuck is designedto accommodate. As should be understood in this art, body 120 may beformed from steel bar stock or any other suitable material.

Body 120 defines a threaded bore 128 in its tail section. Bore 128 is ofa standard size to mate with the drive shaft of a powered or handdriver. While a threaded bore 128 is illustrated, such bore could bereplaced with a tapered bore of a standard size to mate with a tapereddrive shaft. Furthermore, tail section 124 may be formed integrally withthe drive shaft. The bores 126 and 128 may communicate at a centralregion 130 of body 120. Central region 130 may be formed with a socketto accept a drive bit so that the body may be screwed onto the spindleby the bit. Such a socket configuration is described in the '824 patentincorporated by reference above.

Body 120 also defines three passageways 132 to respectively accommodatethe three jaws. In a three-jaw configuration, each passageway, andtherefore each jaw, is separated from each adjacent passageway by an arcof approximately 120°. The longitudinal axes of the passageways 132 andthe jaws 18 are angled with respect to the chuck's longitudinal axis 112but intersect the chuck axis at a common point ahead of chuck body 120.

Body 120 also includes a thrust ring member 136, which in a preferredembodiment forms an integral part of the body. Although not presentlypreferred, the thrust ring may be a separate component from the body'smain portion. As shown in FIG. 5, thrust ring 136 includes a ledgeportion that receives a bearing assembly 142. The bearing assemblyincludes a bearing cage 144 and a pair of washers on either side of thecage. Bearing assembly 142 may comprise any suitable construction, forexample a bearing assembly of the type described in the '318 patentincorporated by reference above.

Tail section 124 can include a rear cylindrical portion having a knurledsurface 156 thereon for receipt of rear sleeve 116. The rear sleeve maybe pressed onto the knurled surface or could be retained in place bypress fit without knurling or by use of a key. It could also be retainedby crimping, staking, riveting, threading or any other suitablemechanism. Where front and rear sleeves 114 and 116 are replaced by asingle sleeve extending substantially the length of body 120, aretaining disk may be pressed or otherwise retained on the tail sectionto maintain the sleeve on the body in the rearward direction. Thesleeves may be made from any suitable material, for example as describedabove.

Nose section 122 is beveled and is adapted to receive a nose piece 157for restraining front sleeve 114 from forward axial movement withrespect to the chuck body. Alternatively, a snap ring or other suitablemechanism may be used to axially restrain the sleeve. Nose piece 157 maybe pressed onto nose section 122 or attached in any other suitablemanner. Rearward axial movement of the sleeve on the body is preventedby thrust ring 136 through bearing assembly 142.

The front sleeve's interior surface 159 defines female threads 158. Thethreads are a modified square thread formation in an eight pitchconfiguration along the length of sleeve 114. It should be understood,however, that any suitable thread shape or formation may be employed,for example including a modified buttress thread. Thus, the squaredinterfaces between the outer surface and the back side and/or front sideof thread 158 may be replaced by a curved interface.

A nut 160 includes a male thread 162 extending about an outercircumferential surface 164. Thread 162 has the same the same pitch asthread 158 so that when thread 162 is received by thread 158, relativerotation between sleeve 114 and nut 160 moves the nut axially within thesleeve. In particular where the nut is molded, thread 162 may havesloped sides, for example at an approximately 5° slope, extending fromsurface 164 to the threads' outer diameter.

Nut 60 includes three equiangularly spaced apart slots 166 extendingaxially through the nut and receiving respective end sections 168 ofjaws 18 therethrough. Each end section has a generally rectangularcross-section that corresponds to the cross-section of its slot 166 sothat the slot slidably receives the jaw end section but preventsrotation of the jaw about the jaw's axis.

Each end section 168 defines a slot 176 extending generally radiallyinto the end section. The end sections extend through the slots 166 sothat the slots 176 are rearward of and parallel to the rear face of nut160.

Each slot 176 receives a respective elongated spring arm 180 thatextends inward from and generally circumferentially within a steel backring 182. Arms 180 bias their distal ends radially inward with respectto back ring 182. Thus, spring arms 180 grip the jaw end sections torestrain rotation of ring 182 about chuck axis 112 when jaws 18 arereceived in slots 132. Furthermore, arms 180 axially fix ring 182 withrespect to the jaws.

As apparent from FIGS. 5 and 6, jaws 18 are unable to pass rearwardlythrough nut 160, and ring 182 restrains the jaws from moving in theforward axial direction with respect to the nut. Furthermore, the jawspass through both nut slots 166 and body slots 132, thereby rotationallysecuring the nut with respect to the body. Since the nut cannot rotatewith respect to the body, rotation of sleeve 114 with respect to thebody moves nut 160 axially with respect to chuck axis 112 by thecooperation between threads 162 and 158. Depending on the sleeve'srotational direction, the nut moves axially forward or backward on thebody to move jaws 18 axially in slots 132 to an open or closed position.

Spring arms 180 help to maintain the jaws in an aligned position inpassageways 132. It should be understood, however, that any suitablemechanism may be used to retain the jaws axially within the jawpassageways. For example, back ring 182 may be replaced by a garterspring or any other suitable retainer, such as an expandable polymercollar, that applies a radially inward force to jaw end sections 168.Alternatively, the nut may be formed with T-shaped slots or cylindricalbores instead of slots 166. Each of three equiangularly spaced T-shapedor cylindrical slots extends radially into the nut and may extendentirely through the nut. Jaw end sections 168 are formed in acorresponding T-shape or semicircle-shape so that the slots slidablyreceive the respective jaw ends. The slots allow the jaw ends to moveradially as the nut moves the jaws between open and closed positions. Adry lubricant coating may be provided on the jaw ends and/or nut slotsto facilitate this movement. The cooperation between the jaw ends andthe nut slots maintains the jaws at the proper angle with respect to thenut so that the jaws are maintained in alignment with the jawpassageways in the assembled chuck.

In still another preferred embodiment, a guide ring may be pressed ontothrust ring 136. Three equiangularly spaced prongs extend rearwardlyfrom the ring against respective jaws 18 rearwardly of jaw passageways132, thereby maintaining the jaws in axial alignment with thepassageways. Back ring 182, a garter spring, or a nut-slot configurationmay be used in conjunction with the guide ring.

Rotation of sleeve 114 clockwise, when viewed from nose section 122,moves nut 160 axially forward with respect to chuck axis 112, therebymoving jaws 18 to a closed position. Conversely, counterclockwiserotation of the front sleeve moves the jaws in an opening direction. Astop 192 is provided at the rear edge of thread 158. When the jaws reacha fully opened position, a rear edge 194 of thread 162 abuts stop 192.This prevents further rotation of the sleeve with respect to the nut andthereby prevents the jaws from binding in the chuck's rear area. Asimilar stop 196 is provided at the front end of thread 158 to stop aforward edge 198 of thread 162 to prevent the jaws from binding in thefully closed position when there is no tool in the chuck bore.

Thread 162 defines one turn around surface 164 of nut 160. A gap betweenthread edges 194 and 198 has an angular width greater than the width ofstop 192. This facilitates the chuck's assembly in that the nut may beplaced directly down onto thread 158 over the stop. Rear sleeve 116 thenprevents the nut from disengaging from the front sleeve when the chuckis in a fully opened position.

Referring now to FIGS. 7 and 10, jaws 18 may also be included in afast-closing chuck 200 having a front sleeve 214, an optional rearsleeve 216 and three jaws 18. A body 220 is generally cylindrical inshape and includes a nose or forward section 222 and a tail or rearwardsection 224. An axial bore 226 is formed in the nose section and issomewhat larger than the largest tool shank that the chuck is designedto accommodate.

Body 220 defines a threaded bore 228 in its tail section. As notedabove, bore 228 may be a tapered bore of a standard size to mate with atapered driveshaft. Furthermore, body 220 may be integrally formed withthe driveshaft. The bores 226 and 228 may communicate at a centralregion 230 of body 220. Central region 230 may be formed with a socketto accept a drive bit so that the body may be screwed onto the spindleby the bit.

Body 220 also defines three passageways 232 to respectively accommodatethe three jaws 18. In a three-jaw configuration, each passageway, andtherefore each jaw, is separated from each adjacent passageway by an arcof approximately 120°. The longitudinal axes of the passageways 232 andthe jaws 18 are angled with respect to the chuck's longitudinal axis 212but intersect the chuck axis at a common point ahead of chuck body 220.

Body 220 includes a thrust ring 236, which may be integrally formed withor separate from the body's main portion.

Tail section 224 can include a rear cylindrical portion having a knurledsurface 256 thereon for receipt of rear sleeve 216. The rear sleeve maybe pressed onto the knurled surface or could be retained in place bypress fit without knurling or by use of a key. It could also be retainedby crimping, staking, riveting, threading or any other suitable securingmechanism. Where front and rear sleeves 214 and 216 are replaced by asingle sleeve extending substantially the length of body 220, aretaining disk may be placed or otherwise retained on tail section 224to maintain the sleeve on the body in the rearward direction.

The outer circumferential surface of sleeve 214 may be knurled or may beprovided with longitudinal ribs or other protrusions to enable theoperator to grip it securely. In like manner, the circumferentialsurface of rear sleeve 216, if employed, may be knurled or ribbed ifdesired. The front and rear sleeves may be fabricated from a suitablematerial such as described above.

The interior surface of sleeve 214 defines three female threads 258A,258B and 258C. The threads are a square thread formation. Nut 260includes three male threads 262A, 262B and 262C that are received inthreads 258A, 258B and 258C, respectively. As described in more detailbelow, nut 260 is rotationally fixed to body 220. Accordingly, rotationof sleeve 214 about the body drives nut 260 axially within the sleeve.Sleeve threads 258A, 258B and 258C and nut threads 262A, 262B and 262Cprovide a one pitch configuration along the length of sleeve 214 in thatone complete relative rotation between sleeve 214 and nut 260 moves thenut approximately one inch axially within the sleeve.

Three female threads and three male threads are used to permit arelatively narrow nut. That is, it is preferable that the nut threadextends substantially entirely about the nut's outer circumference sothat the nut remains balanced during the chuck's operation. Where asingle female/male thread pair is used, the male thread about the nut'scircumference would require that the nut be longer in the axialdirection than where the three-thread configuration is used.Nevertheless, it should be understood that the present inventionencompasses other thread configurations, for example one-thread,two-thread and four-thread arrangements.

Nut 260 is slidably received over a body portion 264 of a thrust plate266. A flange 268 extends radially outward from plate body 264 anddefines a ledge 270 upon which a bearing assembly 272 is received.Bearing assembly 272 includes a first race 274 having recesses 276defined about the radially outward edge of its rearward face. Anopposite race 278 includes a shroud 280 extending axially forwardtherefrom. The shroud defines a plurality of spring arms 282 biasedaxially forward toward washer 274 so that tabs 284 defined at the distalends of arms 282 engage respective recesses 276. When, as describedbelow, nut 262 rotates with respect to thrust plate 266; frictionalforces between washer 274 and thrust plate 266 and between washer 278and nut 260 overcome the link between washers 278 and 274 provided bythe engagement of tabs 284 in recesses 276. Thus, spring arms 282 aredeflected so that each tab 284 moves out of its recess 276 and into thenext recess. Continued rotation of nut 260 with respect to the thrustplate moves tabs 284 in and out of successive recesses, creating aclicking sound notifying the user that the chuck is approaching a fullyclosed position.

In another embodiment, washer 274 includes radially aligned recesses inits rearward face so that each of bearing balls 286 is received in arespective recess. Spring arms 282 are omitted. When relative rotationbetween nut 260 and thrust plate 266 causes relative rotation betweenwashers 278 and 274, each ball 286 rolls out of its recess into the nextrecess. Continued rotation continues movement of the balls throughsuccessive recesses, causing a clicking sound that notifies the operatorthat the chuck is approaching a fully tightened position as describedbelow.

Nut 260 is held rotationally with respect to thrust plate 266 by atorsion spring 290. Torsion spring 290 includes ends 292 and 294 thatare received in opposing holes 296 and 298, respectively.

A detent ball 300 is received in any of three depressions 302 in thrustplate body section 264, depending on the holes 296 and 298 that receivethe torsion spring ends, so that ball 300 is received in a groove 304 inthe inner diameter of nut 260. Ball 300 provides a stop against theedges of groove 304, thereby limiting the range over which nut 260 canrotate with respect to the thrust plate. During normal operation beforethe chuck closes onto a tool shank, ball 300 preferably sits against aside of groove 304 so that, when the chuck closes onto a tool shank,rotation of nut 260 is permitted through the full angular width ofgroove 304. It should be understood that the length of groove 304 may bemodified as desired to permit a greater degree of rotational movement ofnut 260 with respect to thrust plate 266. For example, in one preferredembodiment, the angular width of groove 304 is approximately 240°.

Referring also to FIG. 11, thrust plate 266 includes three equiangularlyspaced apart radial slots 306 that are generally T-shaped. An endportion 308 of each jaw 18 is formed in a cooperating T-shape so thatslots 306 slidably receive the respective jaws. The slots allow the jawends to move radially as the thrust plate moves the jaws between openand closed positions. A dry lubricant coating may be provided on the jawends and/or slots 306 to facilitate this movement. The cooperationbetween the jaw ends and slots 306 maintains the jaws at the properangle with respect to the thrust plate so that the jaws are maintainedin alignment in the jaw passageways in the assembled chuck. Slots 306may also be cylindrical in shape, for example as shown in the embodimentillustrated in FIG. 13, and each jaw end section 308 may be formed in acooperating semi-circular shape so that slots 306 receive the respectivejaws.

Referring again to FIGS. 7 and 10, body nose section 222 includesthreads 310 that engage threads 312 at a front end of sleeve 214. In theillustrated embodiment, threads 312 are formed about the inner surfaceof a metallic insert 314. The outer surface of insert 314 is knurled at316 and is received at the forward end of sleeve 214 in a press fit at318. Threads 310 and 312 form a secondary threaded tightening mechanismhaving a higher pitch than the primary threaded tightening mechanismformed between threads 258 and 262.

Because jaws 18 are received in jaw passageways 232, the jaws areconstrained from rotation about the chuck's axis. The receipt of jawends 308 by slots 306 rotationally holds thrust plate 266 with respectto chuck body 220. When the chuck is between its fully opened positionand a fully closed position in which the chuck jaws are closed on eachother or on a tool, friction between nut threads 262 and threads 258 isnot sufficient to rotate nut 260 against the force of torsion spring290. Thus, in operation and referring to FIG. 8, rotation of sleeve 214in a clockwise direction (when viewed from the front of chuck 200) movesnut 260 axially forward with respect to the sleeve as indicated at arrow318. Nut 260 presses forward against thrust plate 266 through bearingassembly 272, moving the bearing assembly forward with respect to body220. Thrust plate 266, in turn, drives jaws 18 axially forward in theirpassageways 232, thereby moving the chuck toward a closed position.Rotation of sleeve 214 in the opposite direction moves nut 260 axiallyrearward with respect to the sleeve, as indicated by arrow 320. Sincenut 260 is restrained in the axially rearward direction with respect tothrust plate 266 by a snap ring 314, the nut carries thrust plate 266and jaws 18 axially rearward toward the chuck's open position.Accordingly, in both the opening and the closing directions, sleeve 214axially drives the jaws through relative rotation between the sleeve andthe nut. That is, the sleeve drivingly engages the jaws through threads258 and 262.

Sleeve threads 312 also rotate about body threads 310 as sleeve 214rotates. Threads 312 are in the opposite direction of thread 258, andthreads 310 are in the opposite direction of thread 262. Thus, as sleeve214 rotates in the closing (clockwise) direction, sleeve 214 moves onthreads 310 axially forward with respect to the body in direction 318.When the sleeve is rotated in the opposite direction, the sleeve movesrearwardly on threads 310 in direction 320.

Accordingly, when sleeve 214 is rotated in the closing direction, nut260 moves forward in direction 318 within the sleeve, while sleeve 214simultaneously moves forward in direction 318 with respect to the bodyon body threads 310. Because threads 312 and 310 define a higher pitchthan threads 258 and 262, nut 260 moves forward with respect to thesleeve faster than sleeve 214 moves forward with respect to the body.For example, in the one-pitch configuration illustrated in FIG. 8,approximately two full rotations of sleeve 214 are required to move nut260 from its rearwardmost position with respect to the sleeve to itsforwardmost position as shown in FIG. 7. In these two turns, sleeve 214moves only {fraction (1/16)}th inch forward on body 220.

Referring now to FIG. 9, when sleeve 214 is rotated such that jaws 18close onto a tool shank 322, jaws 18, thrust plate 266 and nut 260 areunable to continue their forward axial movement. Accordingly, continuedrotation of sleeve 214 tightens thread 258 against thread 262. Thefrictional force between threads 258 and 262 overcomes the resistance oftorsion spring 290, and nut 260 rotates with sleeve 214 with respect tothe thrust plate and the chuck body. This rotation carries sleeve 214forward on body threads 310, thereby pressing nut 260 forward againstthrust plate 266 through bearing assembly 272. The thrust plate, inturn, further presses jaws 18 down onto tool shank 322. As discussedabove, rotation between nut 260 and thrust plate 266 produces a clickingsound from bearing 272 and is limited by the angular width of groove 304in nut 260 (FIG. 10).

As threads 312 tighten onto threads 310, the forward force of sleeve 214against nut 260 further tightens threads 258 and 262. When the operatorreleases sleeve 214, the sleeve and nut remain in their tightenedrotational positions with respect to the chuck body.

Accordingly, chuck 200 includes a primary tightening mechanism and asecondary tightening mechanism. The primary tightening mechanism,threads 258 and 262, rapidly moves jaws 18 radially toward and away fromthe chuck axis. The low pitch of these threads, however, provides arelatively low mechanical advantage as the jaws tighten onto the tool. Ahigher advantage is supplied by the higher-pitch threads 312 and 310,and it is this secondary tightening that finally tightens jaws 18 ontothe tool shank.

As indicated above, the primary thread is a one-pitch thread, and thesecondary thread is a 32-pitch thread. It should be understood, however,that the pitch values, and the pitch ratio, can vary as suitable for theneeds and construction of a given chuck. Generally, the primary pitch issuch that the chuck opens and closes rapidly and rotationally locks inthe closing direction when the jaws close on each other or a tool. Thatis, when the jaws close, a human operator is unable to relatively rotatethe threads in the closing direction. The secondary thread pitch is suchthat when the jaws close, the threads provide sufficient mechanicaladvantage that the operator is able to continue relative rotation in theclosing direction.

To open the chuck, the operator rotates sleeve 214 in the openingdirection. Sleeve 214 moves axially rearward in direction 320 withrespect to chuck body 220 on threads 310. This releases the wedgebetween threads 258 and 262, thereby allowing torsion spring 290 tocarry the nut back to its original rotational position with respect tothrust plate 266 and the chuck body. Continued rotation of sleeve 214moves the nut, thrust plate and jaws axially rearward and away from thetool shank.

FIGS. 12 and 13 illustrate a further embodiment of chuck 200. The chuckis a single-sleeve chuck, and the outer surface of sleeve 214 extends tothe rear of chuck body 220. A cover plate 324 is axially retained onbody 220 by snap rings 326 and 328. Sleeve threads 312 and body threads310 (FIG. 7) are replaced by threads 330 on the inner circumferentialsurface of nut 260 and threads 332 on the outer circumferential surfaceof the body portion of thrust plate 266. Bearing assembly 272 isdisposed between sleeve 214 and body thrust ring 236. A snap ring 334holds sleeve 214 in the axially forward direction on body 220.

In this embodiment, threads 258 and 262 are in an eight-pitchconfiguration. Nut 260 defines two threads 262A and 262B about its outercircumference. The inner surface of sleeve 214 defines two threads 258Aand 258B that receive threads 262A and 262B, respectively. Threads 330and 332 define a 32-pitch.

Friction between threads 258 and 262 is normally insufficient toovercome the force of torsion spring 290 keeping the nut and thrustplate rotationally together. Accordingly, when chuck 200 is between afully opened and fully closed position, rotation of sleeve 214 in aclockwise direction (when viewed from the front of chuck 200) drives nut260 axially forward with respect to sleeve 214 and body 220 in direction318. Nut 260 is axially held to thrust plate 268 by threads 330 and 332.Thus, movement of nut 260 in direction 318 also moves thrust plate 266,thereby moving jaws 18 in passageways 232 toward the chuck axis.

When the jaws clamp onto a tool, jaws 18 exert a rearward force tosleeve 214 through thrust plate 266 and nut 260. Continued rotation ofsleeve 214 wedges threads 258 and 262. Although a wedge also developsbetween threads 330 and 332, the rotational force applied to the nut bysleeve 214 is greater than the resistance provided by threads 330 and332, due to the much lower pitch of threads 258 and 262. The rotationalforce also overcomes the resistance of spring 290 (about 5 to 10inch-lbs). Thus, nut 260 begins rotating with the sleeve on threads 332against the spring.

Threads 330 have the same orientation as threads 258, and threads 332have the same orientation as threads 262. Thus, rotation of nut 260 withsleeve 214 in the closing direction rotates the nut on threads 332 sothat the nut and thrust plate move axially apart from each other. Sincebearing assembly 272 and the body thrust ring prevent the sleeve and nutfrom moving rearwardly, this rotation forces thrust plate 266 axiallyforward, thereby further pressing jaws 18 down onto the tool shank.Continued rotation wedges threads 330 and 332. This wedge overcomes theforce of torsion spring 290 so that, when an operator releases thesleeve, the chuck remains in the fully tightened position.

To open the chuck, the operator rotates sleeve 214 in the opening(counterclockwise) direction. This rotates nut 260 in the openingdirection with respect to thrust plate 266, moving thrust plate 266, andtherefore jaws 18, axially away from the tool shank. When the nutreturns to its original rotational position on the thrust plate, furtherrotation of sleeve 214 moves the nut, thrust plate and jaws axiallyrearward, away from the tool.

It should be understood that various jaw configurations, including thearrangement illustrated in FIG. 2, may be employed with the chucks ofFIGS. 7-13.

While one or more preferred embodiments of the invention have beendescribed above, it should be understood that any and all equivalentrealizations of the present invention are included within the scope andspirit thereof. The embodiments depicted are presented by way of exampleonly and are not intended as limitations upon the present invention. Forexample, while the sleeve in the embodiments illustrated in FIGS. 7-13forms an exterior surface of the chuck, a chuck in accordance with thepresent invention could include a sleeve that is an interior componentthat rotates with respect to the body to drive the jaws. Thus, it shouldbe understood by those of ordinary skill in this art that the presentinvention is not limited to these embodiments since modifications can bemade. Therefore, it is contemplated that any and all such embodimentsare included in the present invention as may fall within the literal andequivalent scope of the appended claims.

What is claimed is:
 1. A chuck for use with a manual or powered driverhaving a rotatable drive shaft, said chuck comprising: a. a generallycylindrical body having a nose section and a tail section configured torotate with said drive shaft, said nose section having an axial boreformed therein and a plurality of angularly disposed passageways formedtherethrough and intersecting said axial bore; b. an inner sleeve havinga central bore and a threaded outer circumferential surface, whereinsaid body is received within said central bore; c. a plurality of jawsslidably received in respective said angularly disposed passageways,each of said jaws having a jaw face formed on one side thereof; d. anannular nut in driving engagement with said plurality of jaws, whereinsaid annular nut defines a threaded interior surface and is receivedabout and threadedly engages said outer surface of said inner sleeve sothat relative rotation between said inner sleeve and said annular nutmoves said annular nut and said inner sleeve axially with respect toeach other; e. a spring disposed between said annular nut and said innersleeve, said spring biasing against relative rotation between saidannular nut and said inner sleeve; and f. an outer gripping sleeve,wherein said outer gripping sleeve is disposed rotatably about saidannular nut.
 2. The chuck as in claim 1, wherein said nut threadedlyengages said outer gripping sleeve.
 3. The chuck as in claim 1, whereinsaid jaws are axially fixed to said inner sleeve.
 4. The chuck as inclaim 1, wherein said outer gripping sleeve is rotatable with respect tosaid inner sleeve.
 5. The chuck as in claim 1, wherein said outergripping sleeve extends rearwardly even with a back edge of said tailsection.